An industrial robot or the like including a gravity axis uses a brake drive controlling device that controls a brake braking a driven body such as an arm to prevent the driven body from dropping at the time of stopping a motor.
Such a conventional brake drive controlling device controls drive of the brake by electric power stored in a direct current (DC) link unit connected to an alternating current (AC) power supply via a converter (for example, Patent Literature 1).                Patent Literature 1: JP-A-7-328966        
However, the following problem exists in the conventional brake drive controlling device. Namely, at least either influence of energy stored in the brake, or influence of fluctuation in a voltage between both ends of the brake due to fluctuation in a voltage of the DC link unit caused by acceleration, deceleration, or the like of the motor sometimes hinders the brake from being promptly switched from a released state to a fastened state.
An object of the present invention is to provide a brake drive controlling device capable of promptly switching a brake from a released state to a fastened state.